This invention relates to a leading edge configuration for compressor blades of gas turbine engines.
Compressor blades are the foremost rotating components of a gas turbine engine and subject to considerable loads by centrifugal forces, gas pressure and vibration of the airfoils stimulated by the flow medium, but in particular also by ingested foreign bodies and bird strikes. The blades have a supersonic profile with the leading edge being as thin as possible and featuring a sharp form. Such a requirement on the shape disagrees, however, with the loading and damage situation which the leading edge may encounter by the impingement of foreign objects.
Erosion and other damage caused by the impingement of foreign bodies occur particularly marked on the leading edge and the pressure side of the compressor blade. Provision of a robust compressor blade leading edge with an enlarged radius to counteract foreign object damage in this area conflicts, however, with the considerable aerodynamic losses and reduction of engine performance arising therefrom.
In order to anticipate further deterioration of a compressor blade damaged in service by foreign bodies, all compressor blades must, from time to time, be regrouped and reprofiled in the area of the leading edge. Such regrinding can, however, never be accomplished in an optimal manner, even apart from the fact that regrinding and reprofiling incur considerable work effort. This means that such grinding increases the profile of the leading edge and, in consequence, the aerodynamic loss. Moreover, the leading edge cannot be regrouped infinitely.
The compressor blades of a gas-turbine engine are additionally and significantly loaded by the impact resulting from the impingement of a bird on the compressor blades. Also in this case, a small leading edge radius, i.e. a pointed, sharp form of the leading edge of the compressor blade is advantageous, as such a sharp leading edge will cut through the bird straight away, thus considerably reducing the impact on and the loading of the blade. However, the design of a leading edge in consideration of this requirement again conflicts with the risk of rapid damage by erosion, the resultant maintenance effort and the aerodynamic loss.